Compare this to the definition of chronic limb ischaemia which is rest pain of more than two week duration.
In a 1997 publication the SVS/ISCVS (Society for Vascular Surgery/International Society for Cardiovascular Surgery) suggested a scoring system for a number of vascular disorders 3 Note that the 4th ed companion series wrong references the original 1986 paper2 and that cap refill is longer part of the classification. The acute limb ischemia table is below:
The major of cases are due embolism from a distant source (e.g. myocardium) or thrombosis of a pre-existing atherosclerotic plaque.
These are only really seen when a proximal artery is completely occulted and there are no pre-existing collateral vessels. Otherwise milder versions as described in the table above are seen. The severity at presentation that is the most important factor in outcome. Less severe forms are seen where there has been chronic disease and an acute event occurs on top. In this scenario collateral vessel may well have already formed. The absence of a pulse in the contra-lateral leg or history of pre-existing claudication should alert you to this. This is important as suggests thrombosis in-situ.
- All patient need to be initial managed with the basics of resusutation.
- An oxygen mask should be placed on all patients
- Obtain IV access and send bloods for:
- Renal function
- Full blood count
- Clotting
- Glucose
- Group and save
- CK (but is if dubious value in the initial management)
- Start an IV fluids and consider a urinary catheter for fluid balance management
- Give a bolus of 5000u un-fractionated heparin and also start a IV heparin infusion or low-molecular weight treatment dose heparin. The reasoning here is to prevent thrombus propagation. But there is little evidence that it actually improves outcome. Remember that you need to treat the patient as a whole and if regional anaesthesia is going to be required then heparin should be withheld until after the insertion of spinals etc
- Analgesia should be prescribed and given. IV morphine should be titrated to pain
- An ECG (looking for AF / MI) and plain chest radiograph (heart failure) should be carried out.
- As part of the clinical examination ensure that the proximal arterial tree has been throughly examined.
- The presence of a abdominal or popliteal aneurysm warrants duplex ultrasound
- The further management is then dictated by the clinical assessment and findings
The irreversibly ischaemic limb
A minority of patients will present in the late stages of acute limb ischaemia, category III in the table above. Revascularisation in this circumstance would not result in limb salvage and in fact is contra-indicated as the release of toxins may be fatal.
The therapeutic manovue therefore may be primary amputation, but this should only occur after the patient has been properly resusutated and stabilised.
In some patients there is none or little chance of survival even with amputation in which case a terminal care pathway should be instituted.
The threatened limb
| In a patient that has an acutely ischaemic limb and normal pulses in the contra-lateral limb with no history of claudication it is more than likely that an embolism is the cause. |
This refers to category II in the table above. These patients require urgent intervention to prevent limb loss. If the cause is considered to be because of embolic disease the patient should be taken straight to theatre. Pre-operative investigations such as arteriography will mearly delay things.
The non-threatened limb
In the absence of paralysis, sensory loss or a tight calf there is some time to evaluate the limb before treatment needs to commence. In the majority of centres that will involve a arteriogram. Although an invasive procedure, it has the advantage that imagining can be directly followed by therapy in the same sitting. The other imaging modalities to consider are duplex ultrasound, CT arteriogram and MR arteriogram. The choice will probably be dictated by local availability and preferences.
Surgery or Thrombolysis
For the treatment of acute limb ischaemia this question is subject to much controversy.
The main advantages for thrombolysis is that it is less invasive and may uncover a underlying stenosis as the cause of thrombosis in-situ which can later undergo angioplasty. The major risk is that of significant haemorrhage which occurs in up to 9% of patients.
The evidence:
Review by Diffin and Kandarpu. 42 papers. Majority non-randomised. Thrombolysis associated with better limb salvage and lower mortality than surgery.
Randomised trials:
- Ouriel et al from New York 1994 6. One of the first studies to show an advantage of thrombolysis over surgery. However, small numbers and high cardiac and respiratory deaths in the surgical group.
- The STILE study 1994. More patients. No difference in mortality but introduced the concept of amputation free survival. A sub-group analysis of patients with ischaemia for less than 14 days showed that the amputation rate was lower amongst the thrombolysis group. Big criticism is that the radiologists failed to correctly insert a thrombolysis catheter in 1/3 of the patients.
- The TOPAS trial 1996 and 1998 8,9. Phase I was to establish the urokinase dose to be used. Phase II randomised 544 patients. Amputation free survival for urokinase thrombolysis vs. surgery was similar at six months (72% vs. 75%) and one year (65% vs. 70%).
- Five trials reviewed with 1283 patients. Last updated in Feb 2009.
- No difference in limb salvage rate or mortality between thrombolysis and surgery at 30 days, 6 months and one year.
- Complications were certainly worse in the thrombolysis patients
- 30 day stroke rate 1.3% vs. 0%
- Major haemorrhage at 30 days 8.8% vs. 3.3%
- 30 day distal embolisation rate 12.4% vs. 0%
It would seem that the trial evidence shows no benefit, but does show non-inferiority of thrombolysis. Therefore the treatment needs to be selected to suit the individual patient and experience of local services.
The technical steps of surgical intervention (femoral embolectomy) and of radiological intervention (inter-arterial thrombolysis) will be discussed in the operative howto section.
References:
1) Norgeren L, Hiatt WR, Dormandy JA. Inter-society consensus for the management of peripheral arterial disease. Eur J Vasc Endovasc Surgery 2007; 33:S1-75
2) Rutherford RB, Flanigan DP, Gupta SK et al Suggested standards for reports dealing with lower extremity ischemia. J Vasc Surg 1986; 4:80-94
3) Rutherford, et al. Recommended standards for reports dealing with lower extremity ischemia: revised version. J Vasc Surg 1997; 26:517–538.
4) Davies B et al Acute leg ischaemia in Gloucestershire. Br J Surg 1997;84:504-8
5) D P Flanigan, S J Burnham, J J Goodreau, and J J Bergan Summary of cases of adventitial cystic disease of the popliteal artery 1979 February;189(2): 165–175.
6) Ouriel K, Shortell CK, De Weese JA A comparison of thrombolytic therapy with operative revascularisation in the initial treatment of acute peripheral arterial ischaemia. J Vasc Surg 1994; 19:1201-30
7) The STILE Investigators. Results of a prospective randomized trial evaluating surgery versus thrombolysis for ischaemia of the lower extremity. Ann Surg 1994; 220:251-68
8) Ouriel K, Veith FJ, Sasahara AA for the TOPAS investigators. Thrombolysis or peripheral arterial surgery: phase I results. J Vasc Surg 1996;23:64-75
9) Ouriel K, Veith FJ, Sasahara AA for the TOPAS investigators. A comparison of recombinant urokinase with vascular surgery as initial treatment for acute arterial occlusion of the legs. N Eng J Med 1998; 338:1105-11
10) Berridge DC, Kessel DO, Robertson I. Surgery versus thrombolysis for initial management of acute limb ischaemia. Cochrane Database of Systematic Reviews 2002, Issue 1. Art. No.: CD002784. DOI: 10.1002/14651858.CD002784
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